In the present specification, a tag indicates an object having a radio signal transmitting/receiving device (e.g., an antenna or a light receiving/emitting element), a memory portion, and a communication portion incorporated therein and is used as a shipping label or the like. The present application is an application for claim of priority based on Japanese Patent Application No. 2003-120871, filed Apr. 25, 2003, the entire content of which is incorporated herein by reference.
In recent years, in order to prevent the theft of merchandise sold in a shop or the like, a system for preventing theft or the like has become prevalent. The system attaches a tag to merchandise, places an electric-wave transmission/reception gate for sensing the tag in the vicinity of the entrance/exit of the shop, senses the tag attached to the merchandise when it passes through the gate, and generates a beep tone. In such a system using a tag, it is possible to read data in a memory portion provided in the tag from an external terminal or write data therein. The system and the tag are used widely not only for anti-theft measures but also for product assortment in a factory, product delivery, inventory management, and the like through the reading and writing of merchandise data.
The tag mentioned above is mostly of the type which performs the reading/writing of data by using a radio signal and has a configuration as shown in, e.g., FIG. 15. As shown in FIG. 15, a radio tag 151 is a module comprised of an IC 152 for radio communication in a small size of several millimeters square or less and a coil antenna 153. The radio tag 151 is capable of performing non-contact data exchange by using a dedicated reader/writer device 154 (see, e.g., JP-A No. 62934/1997).